STRATIGRAPHY ALONG THE ROCKY MOUNTAIN TRENCH 367 



an occurrence which suggests the extension of an arm of the Mac- 

 Kenzie Devonian sea into the northern part of the trench. The 

 fossil forms in this fauna which are also known in the MacKenzie 

 Devonian include the following species: 



Martinia meristoides Spirifer tulia 



Reticularia fimbriata Atrypa reticularis 



Schizophoria macfarlini Astraespongia hamiltonensis 



S. striatula Heliophyllum halli 



a faunal group which suggests late Middle or early Upper Devonian 

 age. 



Whether this invasion from the MacKenzie basin was con- 

 temporaneous with that from the south, with the two submergences 

 separated by a land barrier in the Lake Windermere district, is 

 not established, but the invasion from the north was probably 

 somewhat later than that from the south. 



Mis sis sip plan. — ^The Mississippian is known to occur only in 

 the southern portion of the trench in the vicinity of Wardner and 

 Bull River, where it was discovered by Schofield.^ Dr. Raymond 

 identified the following species: 



Camarophoria explanata Cleiothyridna crassicardonalis 



Camaroechia cf. C. metallica Spirifer cf. S. centronatus 



Composita madisonensis Productella cooperensis 



RELATION OF PRE- CAMBRIAN TO CAMBRIAN 



The stratigraphic relation of the Cambrian sediments to the 

 pre-Cambrian formations in the Canadian Cordillera has been 

 the subject of considerable discussion. Daly considers the two 

 series to be essentially conformable, while Walcott and Schofield 

 think them unconformable. 



The situation along the main line of the Canadian Pacific is 

 well summed up by Daly in his report of the ''Reconnaissance 

 between Kamloops and Golden."^ The thick lower Cambrian 

 fossil-bearing members have at their base a conglomerate (the 

 Fairview formation). Below this the Hector Shale is considered 



' S. J. Schofield, Geol. Surv. Can. Mem. 76, p. 57. 

 2 R. A. Daly, Geol. Surv. Can. Mem. 68, pp. 87-93. 



